JP2011009500A - Method and apparatus for manufacturing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing method and apparatus, capable of uniformly forming a film on a wafer by inhibiting a jumping phenomenon of the wafer, preventing a decline in yield and productivity and improving the reliability of a semiconductor device.SOLUTION: The semiconductor manufacturing method includes: carrying a wafer into a reaction furnace; placing the wafer on a lifted push-up shaft; disposing an in-heater for heating the wafer so that a difference in temperature between the central part and the outer periphery of the wafer may be within a predetermined range and an out-heater for heating the outer periphery of the wafer, at a first position; heating up the wafer on the push-up shaft by the in-heater and out-heater; lowering the push-up shaft; holding the wafer on a holding member; disposing the in-heater and out-heater at a second position so that the temperatures of the central part and the outer periphery of the wafer may be substantially the same; heating the wafer on the holding member at a predetermined temperature; rotating the wafer; and supplying a process gas onto the wafer.

Description

  The present invention relates to a semiconductor manufacturing method and a semiconductor manufacturing apparatus used for film formation by supplying a reaction gas to the front surface while heating from the back surface of a semiconductor wafer, for example.

  In recent years, along with demands for lowering the cost and higher performance of semiconductor devices, there has been a demand for higher quality such as improvement in film thickness uniformity as well as high productivity in the wafer film forming process.

  In order to satisfy such a requirement, there is a backside heating method in which a single-wafer epitaxial film forming apparatus is used, for example, a process gas is supplied while rotating at a high speed of 900 rpm or more in a reaction furnace and heated from the backside using a heater. It is used.

  In such a backside heating method, when a wafer at room temperature is introduced into a reaction furnace heated to about 700 ° C. in advance and transferred onto the member, the central member is cooled, There is a problem that the temperature decreases and temperature unevenness occurs. Therefore, a method of heating the central member excessively has been proposed (see, for example, Patent Document 1).

JP 2002-43302 A ([0028] to [0029] etc.)

  As described above, by heating the central portion, it is possible to suppress to some extent the temperature unevenness of the wafer that occurs when a normal temperature wafer is introduced into a high temperature reactor. However, it is actually difficult to control the wafer so that there is no temperature unevenness. In particular, when an oxide film is formed on the back surface, the wafer is warped not only due to its own weight but also due to a temperature difference between the front surface and the back surface, a difference in thermal expansion coefficient, and the like.

  Then, since the wafer is heated and deformed from the concave state to the convex state, the wafer splash phenomenon occurs. Due to this splashing phenomenon, the wafer is displaced from its normal position and cannot be held horizontally, or dropped and damaged, resulting in a decrease in yield and productivity. Problem arises.

  The amount of warp displacement depends on the temperature, and the amount of deformation can be suppressed by suppressing the temperature difference between the central portion and the outer peripheral portion to some extent. As the temperature difference increases, the amount of deformation from the concave state to the convex state increases, but when the temperature difference increases to some extent, the temperature at which the concave state changes to the convex state also increases. That is, when the temperature difference between the central portion and the outer peripheral portion of the wafer becomes large to some extent, even if the wafer is raised to the film formation temperature, it does not deform from the concave state to the convex state.

  The present invention has been made on the basis of such new knowledge, suppresses the wafer jumping phenomenon, uniformly forms a film on the wafer, suppresses yield and productivity, and reduces the reliability of the semiconductor device. An object of the present invention is to provide a semiconductor manufacturing method and a semiconductor manufacturing apparatus capable of improving the performance.

  In the semiconductor manufacturing method of the present invention, the wafer is loaded into the reaction furnace, the wafer is placed on the raised push-up shaft, and the wafer is placed so that the temperature difference between the center and the outer periphery of the wafer is within a predetermined range. An in-heater for heating and an out-heater for heating the outer periphery of the wafer are arranged at the first position, and the temperature of the wafer on the push-up shaft is raised by the in-heater and the out-heater, and the push-up shaft is lowered. The wafer is held on the holding member, and the in-heater and the out-heater are arranged at the second position so that the temperatures at the center and the outer periphery of the wafer are substantially uniform, and the wafer on the holding member is Heating at a temperature, rotating the wafer, and supplying a process gas onto the wafer.

  In the semiconductor manufacturing method of the present invention, the wafer is preferably maintained in a concave state until the push-up shaft is lowered.

  In the semiconductor manufacturing method of the present invention, it is preferable to control the temperature of the outheater to be lower than that of the inheater with the push-up shaft raised.

  Furthermore, in the semiconductor manufacturing method of the present invention, the outheater can be moved up and down between the inheater and the holding member.

The semiconductor manufacturing apparatus of the present invention includes a reaction furnace in which a wafer is formed into a film, a gas supply mechanism for supplying process gas to the reaction furnace, a gas discharge mechanism for discharging gas from the reaction furnace, A wafer drive mechanism having a push-up shaft for raising and lowering the wafer, a holding member for placing the wafer, an in-heater for heating the wafer to a predetermined temperature, installed under the holding member,
An out-heater for heating the outer periphery of the wafer to a predetermined temperature at the lower part of the holding member and on the upper part of the in-heater;
A heater drive mechanism for independently moving the position of the in-heater and out-heater up and down, and a temperature control mechanism for controlling the temperatures of the in-heater and out-heater, respectively.
And a rotation mechanism for rotating the wafer.

  According to the present invention, in the film formation process of a semiconductor device, the splashing phenomenon of the wafer is suppressed, the film is uniformly formed on the wafer, the yield and productivity are suppressed, and the reliability of the semiconductor device is improved. It becomes possible.

FIG. 6 is a cross-sectional view of a semiconductor manufacturing apparatus of one embodiment of the present invention. 4A and 4B illustrate a manufacturing process of a semiconductor device according to one embodiment of the present invention. 4A and 4B illustrate a manufacturing process of a semiconductor device according to one embodiment of the present invention. The figure which shows the relationship between the displacement amount by the temperature difference of a center part and an outer peripheral part when temperature is raised in the wafer in 1 aspect of this invention, and temperature.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of an epitaxial growth apparatus which is a semiconductor manufacturing apparatus of this embodiment. As shown in the figure, for example, a process gas including a source gas such as trichlorosilane (TCS) or dichlorosilane is applied to the reaction furnace 11 in which a wafer w having a diameter of 200 mm is formed on the wafer w from above the reaction furnace 11. A gas supply port 12 connected to a gas supply mechanism (not shown) for supplying to is provided. A gas discharge port connected to a gas discharge mechanism (not shown) for discharging gas to, for example, two places below the reaction furnace 11 and controlling the pressure in the reaction furnace 11 to be constant (normal pressure). 13 is installed.

  A rectifying plate 14 for supplying the process gas supplied from the gas supply port 12 to the wafer w in a rectified state is installed on the upper portion of the reaction furnace 11. A susceptor 15 that is a holding member for holding the wafer w is disposed below the susceptor 15. Further, a ring 16 connected to a susceptor 15 and connected to a rotation drive mechanism (not shown) including a rotation shaft and a motor is installed.

  Below the susceptor 15, an in-heater 17a for heating a wafer w made of, for example, SiC is installed. Furthermore, between the susceptor 15 and the in-heater 17a, an out-heater 17b for heating the outer peripheral portion of the wafer w made of, for example, SiC is installed. A disc-shaped reflector 18 for efficiently heating the wafer w is installed below the in-heater 17a. A push-up shaft 19 is provided so as to penetrate the in-heater 17a and the reflector 18 and connected to a wafer drive mechanism (not shown) for moving the wafer w up and down.

  The reactor 11 is connected to an in-heater 17a and an out-heater 17b, and includes a temperature control mechanism 20 for controlling the respective temperatures, a motor, a cylinder (not shown), and the like. Heater drive mechanisms 21a and 21b for driving are provided.

  Using such a semiconductor manufacturing apparatus, for example, a Si epitaxial film is formed on a φ200 mm wafer w on which a back-side oxide film of 900 nm is formed.

  First, as shown in FIG. 2, the gate (not shown) of the reaction furnace 11 is opened, and the wafer w is carried into the reaction furnace 11 in which the inside of the furnace is heated to 700 ° C. by the robot hand 22. At this time, the wafer w does not vary in temperature distribution and is slightly concave due to its own weight.

Next, the push-up shaft 19 is raised, the wafer w is placed on the push-up shaft 19, the robot hand 22 is carried out of the reaction furnace 11, and the gate (not shown) is closed. For example, H ₂ gas or the like is introduced into the reaction furnace 11 through a gas supply port 12 from a gas supply mechanism (not shown).

At this time, the H ₂ gas at room temperature is introduced onto the wafer w and convects in the reaction furnace 11, so that the temperature at the center of the wafer w is particularly lowered. Therefore, as shown in FIG. 3, the heater driving mechanisms 21a and 22a raise the in-heater 17a, lower the out-heater 17b, or both, and the temperature distribution in the wafer w plane is changed to the temperature at the center. Is controlled so as to be high, and preheating is performed.

  For example, when the distance between the back surface of the wafer w and the in-heater 17a and out-heater 17b at the time of film formation is used as a reference, the in-heater 17a is raised so that the distance from the back surface of the wafer w is reduced by about 0 to 10%. The outheater 17b is lowered so as to increase by about 0 to 15%. In addition, the in-heater 17a and the out-heater 17b are arranged so as not to contact each other with a gap of about 2 mm, for example.

  By arranging in this way, when the ultimate temperature of the wafer w is 1100 ° C., for example, it is controlled so that it is not less than the critical temperature difference (for example, 40 ° C. or more) that does not deform into a convex state even if it reaches 1100 ° C. Can do.

  At this time, the critical temperature difference can be obtained from the relationship between the amount of displacement and the temperature due to the temperature difference between the central portion and the outer peripheral portion when the wafer is heated to a predetermined temperature.

  For example, a case where the temperature of the central portion of the wafer w having a φ200 mm, 0.725 mm thickness, and a 900 nm thick backside oxide film is raised from 700 ° C. to 1200 ° C. will be described as an example.

  As shown in FIG. 4, when the temperature difference between the central part (for example, 20 mm from the center) and the outer peripheral part (for example, 90 mm from the center) is 30 ° C. or less, the amount of displacement is also small, and the convex state is from a gently concave state to about 900 ° C. To change.

  Then, when the temperature difference exceeds 30 ° C. and below 36 ° C., it changes suddenly from a concave state to a convex state at 900 ° C., and when it exceeds 36 ° C., it changes from a concave state to a convex state depending on the temperature difference. The temperature to be increased also increases.

  Further, when the temperature difference is 40 ° C., even if the temperature difference is increased to 1200 ° C., the concave state does not change to the convex state. At this time, the temperature difference of 40 ° C. is set as a critical temperature difference that remains concave even when the wafer is raised to 1200 ° C. Then, the temperature distribution in the wafer surface is controlled so as to be equal to or greater than this temperature difference.

  Next, the push-up shaft 19 is lowered to place the wafer w on the susceptor 15. Then, the heater driving mechanisms 21a and 22a are used to lower the in-heater 17a, raise the out-heater 17b, or move both of them, and place them at predetermined positions. Further, the temperature control mechanism 21 controls the in-heater 17a to 1400 ° C. and the out-heater 17b to about 1500 ° C. so that the in-plane temperature of the wafer w is uniformly 1100 ° C.

  Then, the rotational drive mechanism rotates the wafer w at, for example, 900 rpm, and supplies process gas from the gas supply port 12 through the rectifying plate 14 in a rectified state onto the wafer w. The process gas is prepared to have a TCS concentration of 2.5%, for example, and supplied at, for example, 50 SLM.

  On the other hand, gas such as excess process gas including TCS, dilution gas, and reaction by-product HCl is discharged from the gas discharge port 13, and the pressure in the reaction furnace 11 is controlled to be constant (for example, normal pressure). Then, an Si epitaxial film is grown on the wafer w.

  Thus, until the wafer w is loaded into the reaction furnace 11 and placed on the susceptor 15, the in-heater 17 a and the out-heater 17 b are set so that the temperature difference between the central portion and the outer periphery of the wafer w becomes larger than the critical temperature difference. To preheat. By performing preheating in this manner, the wafer w is maintained in a concave state, and the wafer splash phenomenon can be suppressed. Then, it is possible to uniformly form a film on the wafer, suppress a decrease in yield and productivity, and improve the reliability of the semiconductor device.

(Embodiment 2)
In the present embodiment, the same epitaxial growth apparatus as in the first embodiment is used, but the position of the heater during the preheating is different.

  After the wafer w is loaded and placed on the push-up shaft 19 as in the first embodiment, the heater driving mechanisms 21a and 21b are used to lower the in-heater 17a or raise the out-heater 17b. By both, preheating is performed by controlling the temperature difference between the central portion of the wafer w and the outer peripheral portion to be 30 ° C. or less.

  For example, when the distance between the back surface of the wafer w and the in-heater 17a and out-heater 17b at the time of film formation is used as a reference, the in-heater 17a is lowered so that the distance from the back surface of the wafer w is increased by about 0 to 10%. About the outheater 17b, it raises so that it may become about 0 to 5% small. In addition, the in-heater 17a and the out-heater 17b are arranged so as not to contact each other with a gap of about 2 mm, for example.

  By arranging in this way, when the ultimate temperature of the wafer w is set to 1100 ° C., for example, even if it rises to 1100 ° C., the deformation is controlled to be within a gentle temperature difference range (for example, 30 ° C. or less). Can do.

  By performing preliminary heating in this way, deformation of the wafer w can be suppressed and the wafer jump phenomenon can be suppressed. As in the first embodiment, it is possible to uniformly form a film on the wafer, suppress a decrease in yield and productivity, and improve the reliability of the semiconductor device.

  In these embodiments, the wafer w may have a predetermined temperature distribution by further controlling the temperatures of the in-heater 17a and the out-heater 17b. That is, the controllable temperature range is increased by controlling the temperature of the in-heater 17a to be higher than the temperature of the out-heater 17b in the first embodiment and lower than the temperature of the out-heater 17b in the second embodiment. be able to.

  In these embodiments, the wafer w is placed directly on the push-up shaft 19 during loading and preliminary heating. However, the wafer w may be placed on the push-up shaft via the susceptor 15. At this time, the susceptor may be divided, and the parts of the divided susceptor may be placed on other parts.

  According to the present embodiment, a film such as an epitaxial film can be stably formed on the semiconductor wafer w with high productivity. As well as improving the yield of the wafer, it is possible to improve the yield of the semiconductor device formed through the element formation process and the element isolation process and to stabilize the element characteristics. In particular, an excellent element can be obtained by being applied to an epitaxial formation process of a power semiconductor device such as a power MOSFET or IGBT that requires a thick film growth of 100 μm or more in an N-type base region, a P-type base region, an insulating isolation region, or the like. It becomes possible to obtain characteristics.

In the present embodiment, the case of forming the Si single crystal layer (epitaxial film) has been described. However, the present embodiment can also be applied when forming the poly-Si layer. Further, the present invention can also be applied to film formation other than Si film such as SiO ₂ film and Si ₃ N ₄ film, and compound semiconductor such as GaAs layer, GaAlAs and InGaAs. Various other modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 11 ... Reactor 12 ... Gas supply port 13 ... Gas discharge port 14 ... Current plate 15 ... Susceptor 16 ... Ring 17a ... In heater 17b ... Out heater 18 ... Reflector 19 ... Push-up shaft 20 ... Temperature control mechanism 21a, 21b ... Heater drive mechanism 22 ... Robot hand

Claims (5)

Bring wafers into the reactor,
Place the wafer on the raised push-up shaft,
An in-heater for heating the wafer and an out-heater for heating the outer periphery of the wafer are arranged at the first position so that the temperature difference between the center and the outer periphery of the wafer has a predetermined range. The temperature of the wafer on the push-up shaft is increased by the in-heater and the out-heater,
Lowering the push-up shaft to hold the wafer on a holding member;
The in-heater and the out-heater are arranged at a second position so that the temperatures of the center and outer periphery of the wafer are substantially uniform, and the wafer on the holding member is heated at a predetermined temperature,
Rotate the wafer,
A semiconductor manufacturing method, wherein a process gas is supplied onto the wafer.   2. The semiconductor manufacturing method according to claim 1, wherein the wafer is maintained in a concave state until the push-up shaft is lowered.   The semiconductor manufacturing method according to claim 1, wherein the temperature of the outheater is controlled to be lower than that of the inheater in a state where the push-up shaft is raised.   The semiconductor manufacturing method according to claim 1, wherein the outheater is moved up and down between the inheater and the holding member. A reactor in which wafers are deposited, and
A gas supply mechanism for supplying process gas to the reactor;
A gas discharge mechanism for discharging gas from the reactor;
A wafer drive mechanism having a push-up shaft for raising and lowering the wafer;
A holding member for placing the wafer;
An in-heater installed under the holding member and for heating the wafer to a predetermined temperature;
An outheater for heating the outer periphery of the wafer to a predetermined temperature, which is installed at the top of the inheater at the bottom of the holding member;
A heater driving mechanism for independently moving the positions of the in-heater and the out-heater up and down,
A temperature control mechanism for controlling the temperatures of the in-heater and the out-heater, and
A semiconductor manufacturing apparatus comprising: a rotation mechanism for rotating the wafer.

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